TrueNAS Device is causing slow I/O on pool

Having an issue with - TrueNAS Device is causing slow I/O on pool. I have used other drives and change hardware. Both units are HP Micro Servers. One is G9 & other a G8. Both doing same thing. Current drives are WD Pro RED 2TB.

Any ideas?

Are they different RPM?

I am using 3 x WD2002FFSX 2TB WD Red Pro NASware 3.0 all the same drives.

Do you have the same pool settings like async?

Also it might be worth to see if there are any bugs related to your issue on the IXSystems jira.

I think I have found the problem. The on-board controller seems to have issues with TrueNAS. I installed a Dell controller and everything is now working 100%